There’s lots to like about Alter Eco, a San Francisco-based food company that aims to do social and environmental good. The company supports poor farmers, sources from cooperatives, offsets its carbon footprint, etc. Better yet, its products are tasty. I’m partial to the organically-grown, fairly-traded Dark Quinoa Chocolate Bar, which you could think of as a politically correct (and pricey) version of Nestle’s Crunch.

There would be even more to like about Alter Eco if it was a bigger company. The challenge for its founders, Mathieu Senard and Edouard Rollet, who I visited last fall in San Francisco, is to figure how to drive growth without compromising their values.

My story about Alter Eco, which ran this week at Guardian Sustainable Business, begins like this:

What would a truly sustainable food company look like? That’s hard to say, but a small company called Alter Eco, which sells quinoa, rice, chocolate and sugar grown in Latin America, Asia and Africa, offers a clue or two.

Striving to hit the very highest environmental and social standards, Alter Eco sources only Fair Trade commodities, buying from small-farm co-operatives. Its products are certified organic. It offsets its carbon emissions. And, when the founders could not find packaging that satisfied them, they designed their own: a bio-based, backyard-compostable package with no petroleum or chemicals or genetically modified corn.

The trouble is, Alter Eco is small – it reported just $7m in revenues in 2012. When I visited co-founders Senard and Edouard Rollet at Alter Eco’s headquarters in San Francisco, they told me that sales topped $10m in 2013 and are expected to jump 44% to $14.5m this year. “We can go to $100m in the next five to 10 years,” Senard claims.

That said, big food companies measure their sales in billions, not millions. General Mills booked sales of nearly $18bn in the 2013 fiscal year, meaning it does more business in a day than Alter Eco does in a year. For small, socially responsible companies like Alter Eco to have a big impact, they either need to grow rapidly, or influence their much larger competitors, or both.

Part of the problem facing Alter Eco is pricing. Paying Fair Trade prices, sourcing from smaller coops and carbon offsets all cost money, costs which have to be passed along to consumers. (That 2.82 oz. quinoa bar retails for about $3.50.) Higher prices, of course, limit demand–and growth. This is a challenge that has been overcome by a handful of values-driven food companies, including Starbucks and Stonyfield Yogurt. But not many.